This blog discusses current weather, weather prediction, climate issues, and other topics

Sunday, August 27, 2017

How Will Human-Forced Climate Change Affect the Pacific Northwest?

It is an issue of extreme interest to almost everyone: how will human-forced climate change affect our region?

This blog will review what I believe is the state-of-the-science, one that will avoid hype or politicization of the issue. One based on peer-reviewed publications and the best models we have available. And an analysis that will be honest about what we don't know and the uncertainties.

What Climate Changes Have Occurred During the Past Decades in the Pacific Northwest?

Mankind has already changed the surface climate in our region in profound ways. We have massively irrigated parts of eastern Washington, reducing summer temperatures there (2-5F). A high resolution satellite image illustrates the vast irrigated areas in the Columbia Basin.

We have cut down the trees in western Washington, replacing them with concrete and buildings, substantially warming the surface (as much as 5-10F, see satellite based temperatures below). Thus, there are urban heat islands in our built up area, with enhanced local temperatures.

We have created large farms in eastern WA, tearing off the protective surface vegetation, resulting in dust storms. And our mismanagement of eastern Washington forests have resulted in increasing large fires and major smoke outbreaks.

There is more, but the message is clear: human activities have profoundly changed our surface climate in limited areas, without even talking about greenhouse gases in the atmosphere.

What do surface weather observations show, regarding changes in temperature and precipitation over our region during the past decades? Is there a trend?

Here are plots of NOAA/NWS average temperatures over Washington State for January through June for the past 50 years from their climate division data set (I chose a half year so 2017 could be available). For temperature, there was a big spike in 2015 and a secondary one in 1994, but the overall trend is small, with perhaps a degree of warming for the entire period and little trend since the late 1970s . Most of the increase occurred abruptly in the late 1970s, associated with shift in the Pacific Decadal Oscillation (PDO), which is a mode of natural variability. And there was some impact of urbanization.

Precipitation over the State shows little trend, with lots of transient up and downs.

And a plot of the Palmer Drought Index (which includes precipitation and temperature) shows little change.

Regional snow pack on April 1 (right before the big spring melting season) has shown little trend during the past 40 years.

The bottom line is that there has been little change in our regional climate over the past half century. This is in contrast to other regions (like the Arctic and continental interiors). One reason for our static situation is the vast Pacific Ocean, which has not warmed up much during the past 50+ years. This graphic of surface temperature changes over the past 70 years illustrates this.

Our Future Climate

But what about the future? There has been an increasingly rapid upward trend in greenhouse gases (CO2, methane, water vapor), with human-caused increases in CO2 being the dominant forcing agent. The science is clear: increasing greenhouse gases will warm the planet--but there are a lot of nuances and details that are critical.

Mankind has done little to stop the increase in CO2, with a fast upward trend in renewable energy being overwhelmed by surging use of coal, oil, and natural gas (see plot of CO2). Carbon-free nuclear energy is being rejected. CO2 concentrations are actually rising more quickly today than decades earlier.

Basic science tells us that increasing CO2 will warm the planet, but that warming is not and will not be uniform for many reasons. Advanced global climate models (GCMs) allow us to simulate the expected warming distributions..and most of such models (there are about 2 dozen) provide a generally similar geographical distribution (see a forecast for 2100 for an average of several of them, assuming CO2 will keep on going up at roughly the current rate is has been)

The Arctic warms up more than anyplace else (due to melting polar snow/ice and some subtle radiative effects). The continents warm up more than the oceans (the oceans have huge thermal mass that take time to warm), and the eastern oceans typically warm up more slowly than western oceans. The Northwest, downstream of an eastern Ocean, thus will warm up more slowly than most.

Although the global climate models are our most powerful tools for looking forward, they are major issues. First, we have to assume how much CO2 and other gases will be in the atmosphere later in the century. Second, they lack the resolution to get our local climate correct. As shown below (the terrain from the NCAR climate model, CCSM4), the current generation of global models don't have the Cascades, Olympics and other critical geographical features that dominate our local climate.

Third, the climate models have major disagreements in regional areas. In a classic paper, Deser et al., 2012 (Nature Climate Change) ran an ensemble of 40 climate simulations, starting each slightly differently to simulate trends through 2060. The results for the temperatures at Seattle (see below) varied greatly, with a few runs showing no warming and others much more.

Fourth, many of the global climate models have serious flaws. Some can not realistically duplicate the current climate (e.g., double Intertropical Convergence Zones, serious biases, severe problems with organized tropical convection). And some climate scientists believe that the "tuning" to match the 20th century climate makes them overly sensitive to increasing CO2. There is a lot of dirty laundry in the climate modeling business that the general media and others are not aware of. Our current generation of forecast models can not predict seasonal changes with any skill...this is a major warning.

So what do we do? The roughly 2-dozen global models are the best tools we have. Society desperately needs guidance regarding the local impacts of climate change driven by increasing greenhouse gases.

So why not start with the best ones (the ones that match contemporary climate the best) and see what changes they have in common. And we can use the best models to figure out the local impacts by running high-resolution regional climate models that are embedded and nested in the global models. And when we do this, we have to be totally honest about uncertainties and limitations.

Let me show an example of such a regional climate model simulation for this century for the Pacific Northwest. And be prepared to be shocked.

Let's start with surface temperature (2-m temperature) for winter (DJF) assuming mankind keeps on its current track of greenhouse gas increases (a pretty good bet at this point) The change between the 1990s and 2020s is small, with all warming, but not many locations doing so by more than 3F.

Between 1990s and 2050s? More warming, with bands of greater increases.

2090s? Yikes...a different world, with some places warmer by 6-8F.

Why the bands of greater warming? That is where we are losing snow at lower elevations. Snow reflects solar radiation, so a loss of snow really revs up the heating. You need a high-resolution model to see this effect.

A key issue is that warming is not uniform in time. The warming is slow at first (aided by the slow to warm Pacific), but by the end of the century it really revs up. Another way to see this is a plot of the number of days per decade above 90F at Sea Tac Airport.

Not much change in the 2020s, up a bit in 2050, and BIG increases during the late 2090s. For all of you under 40, you should make a note to yourself to buy an air conditioner in 2050. Maybe two.

I can't stress this enough.... the big changes due to human-caused global warming in the Northwest are AHEAD of us.

The current NW climate has been relatively unchanged so far. But saying this has gotten me in total trouble with some local climate advocates, who call me all kinds of names for talking about this "inconvenient truth." I mean really nasty stuff, like being a "denier", a "contrarian", "dangerous", "losing my mind", and lately being sympathetic to "white supremacists". You deserve the truth, not manipulation, and exaggeration to ensure "you do the right thing".

What about precipitation in our region? Most simulations, either based on global climate models or their regional "downscaled" versions indicate that there will be a small increase (5-10%) in regional precipitation (changes over Puget Sound are shown below). We will retain our water as the earth warms. This makes sense, a warmer atmosphere can "hold" more water, so our precipitation will be juiced up.

But occasionally, it may be juiced up more than we like. The latest simulations suggest that atmospheric rivers---plumes of water vapor coming out of the tropics/subtropics--will get substantially enhanced by global warming, and our extreme precipitation events during such rivers could be 30-40% stronger by the end of the century.

The number of heavy precipitation events will increase dramatically, particularly during the fall (see graphic below showing changes in the number of event between the ends of the 20th and 21st century).

With a big increase in heavy precipitation events, flooding on our major rivers will increase. We will need to deal with this, pulling folks away from such waterways. And yes, not allowing people form living on or near slopes where slope failures could endanger them (e.g., Oso).

As our region warms, the snow level will rise in the mountains, with much more precipitation falling as rain in the middle elevations, where previously there had been snow. We will have less snow in our mountains during the winter and there will be less snowpack on April 1, leaving less snow melt to provide water during the summer and autumn before the rains return.

The predicted change of snow pack by the end of the century is substantial, with losses (red colors) exceeding 40% in some locations. (see graphic)

So what do we do with water in late summer, as snowmelt lessens? Since our annual precipitation will increase, the water will be there, so we may need additional reservoir capacity in some locations. Fortunately, the critical Columbia River drainage may be in relatively good shape because it drains off the very high Rockies, where there will still be a lot of snow, and because of the huge storage capacity behind all the hydroelectric dams.

Thus lack of snow will have another negative impact: snow absorbs water during heavy rain events, so less snow means less buffering of the rain, contributing to flooding, particularly during the fall. Seriously, I would not want to live in the flood plains of our local major rivers.

What about windstorms caused by big midlatitude cyclones? The media keeps on talking about how they will get worse around here. Fortunately, the best climate simulations do NOT suggest this...our storms will be relatively unchanged (see graphic below that was produced for Seattle City Light).

Number of times per year above the 90 percentile wind speed for 1970-2000 (DJF)

The lack of change of windstorms makes sense. Our wind storms are driven by north-south temperatures differences and those will weaken at low levels under global warming (polar regions preferentially warm compared to the tropics in the lower atmosphere).

And our computer models indicate all kinds of unexpected changes in our region with global warming. For example, the amount of low clouds in the late spring and early summer may increase, as the greater heating inland causes preferential pressure falls that draw in cool, cloudy marine air (see graphic). Super June gloom powered by global warming. That will send come Californians back to where they came from!

And in a warming world, the strength of summer disturbances and easterly offshore flow may weaken, taking the edge of western Washington heat waves.

And, dare I say something that will get me in terrible trouble with certain folks? As described in the peer-reviewed literature, warming will have some positive impacts as well, including a more pleasant climate for much of the year, less black ice on the roads, less exposure deaths of homeless folks, improved air quality during the winter, among others.

Enough. I wanted all of you to be exposed to a description of the current science not provided by some local media outlets, a few of which are providing a highly skewed, inaccurate view of what is expected. Some of outlets (e.g., Seatttlle's The Stranger) have descending into exaggeration, advocacy, and name calling, as have a few "advocate scientists.".

Society can only make good decisions only if it is given the best estimates our science can provide, and hype/exaggeration/and worse is destructive on many levels. Imagine planning a new reservoir based on exaggerated predictions! Exaggeration and hype also lead to politicization of dealing with climate change, which ensure progress is restrained.

Finally, let me note that understanding the local implications of climate change is an act in progress.

As I will describe in a future blog, several of us are trying to get better answers by running an ensemble of many high-resolution local climate simulations to get at the uncertainties and possibilities. Other atmospheric scientists (some in my department at the UW) are working on improving the global models. Others, such at the UW Climate Impacts Groups, are trying to translate the model predictions into societal implications.

There is much work to be done: in understanding the local implications of climate change, taking steps to prepare our region for what will occur, and to do what we can to lessen emissions of carbon around the world.

42 comments:

1) The Pacific NW, including BC is best positioned in terms of local risk, but that does not translate to absolute risk, in terms of geo political hazard. Our comparatively rosy environment will attract both migration and resource extraction, primarily agriculture, water and hydro electricity. Canada, with its famous "longest unprotected border" will eventually be invaded by his allegedly friendly southern neighbour, as is its habit.

2)While the "ramp up" in effect will only be realized later, mitigation is the duty of the current generation. We know about it, we know what to do but as Cliff points out "Mankind has done little to stop the increase in CO2,"

3) The "imperfection" of the models is long claimed as a reason to do nothing. As an analogy, avalanche risk modelling is far worse to the point of the abjectly primitive, yet no one suggest that we don't manage avalanche risk, based entirely on those precise primitive forecast models, and in general terms, that proves out repeatedly to be a good idea.

So like our inherently more stable maritime snowpack, let's not get too complacent about our favoured geographical position, nor too dismissive of the value of our tools in spotting growing anomalies to our norms.

Excellent blog post. Both interesting and a bit frightening for the long term. You’ve mentioned before that the biggest impact in the PNW might be refugees from other places looking for a place that has not become inhospitable. With prope r science , applied correctly we might still dig our way out before the worst happens, but I’m not overly hopeful.

Interesting and useful column, Cliff, as usual. I'll leave any debate to climate scientists. My question is, as a NW native, I remember many soggy summers and what seemed like reliable winter snowpack. Recently, the weather SEEMS kind of wacky, with record-setting moisture in recent winters (this last one, and the Oso landslide one) and drier summers (this one, and the two years of big fires in the Wenatchee and Okanogan region the past few years.) In January, we experienced the drought-breaking rains in California. Is my memory (born in 51) simply selective, or has there been a more dramatic contrast between wet and dry seasons over the past decade or two? A follow-up blog might look at how weather records keep getting broken, and whether this has any real significance. In the east, we seems to have "storms of the century" about every decade or so (Harvey just the latest) - is the drama just hype?

It's interesting to see that the regions expected to lose 40% of snowpack are right along the crest of the BC Coastal mountains, bad news for Whistler. This is a region of vast glaciers already experiencing glacial receeding. What is the reason for this? These mountains are easily high enough that most of the precip even at the end of the century should fall as snow during the winter.Is it that the global climate change models expect a shift in the average location of the jet stream so more storms are directed into our region instead of B.C? Or is it the models actually showing the loss of the glaciers themselves in these regions? Why is it that region will lose so much more snowpack than the North Cascades, which are not that far from the BC Coastal mountain range?

cfr450ish - look up and read about the Milankovitch cycles. Simply stated, ice ages are caused by, and ultimately end, due to the Earth's axial precession. This is a process that has nothing whatsoever do to with "global warming" as it is discussed here.

I have been looking at those data series for the six regions in Washington for years. I've always been puzzled why, whether it is data for the Puget Sound lowlands or the Central Basin, why until the 1980's there is no apparent trend but then beginning at that time there is an obvious up trend. Most of the causes from human activity began long before the mid-1980's. What would explain the delayed response?

It's purely a short-term observation but it seems to me that historically we nearly always got a couple of wet spells in core summer (say, mid June through mid September) but in the last three years summer has been pretty much sunny straight through with any rain to speak of.

On sensitivity of models to increased CO2. One reason we can suspect that the models are not overly sensitive is that we have other independent estimates of climate sensitivity to external forcings. Recently from events like Mount Pinatubo and in the paleoclimate from global response to orbital forcings.

Re precipitation. Overall increase but I understand some simulations show less summer precip and more winter precip. This could mean more water when we don't need it and less when we do.

Cliff, you're my hero. I'm so tired of the media and hyperbolic claims by all sides. The future doesn't look great and it still makes me extremely anxious, but I'd rather think about it with a level-headed, best tools approach. Thank you for respecting the intelligence of your readers and being as un-biased as possible. --Sara

"I cannot believe such an educated person like Cliff actually believes in human based climate change. Tell me, how did we exit the last ice age? Must have been some serious global warming...."

Lady, seriously, go to college. I'm so tired of seriously RETARDED comments like this. Cliff doesn't "believe" in human-based climate change, because science is NOT about believing. Its about facts, not your stupid teenage girl opinions, or your Trumpian Alternative Facts.

J Said:

"Pure propaganda. As time goes forward, we'll see what actually happens Mr. Cliff."

Also a retard comment. People like you ALWAYS fail to provide any real, counter data. Pure propaganda huh? Yep, these pesky college professor scientists SURE ARE MAKING THEIR MILLIONS off of their corrupt grant checks. Jesus Christ, you and those like you make ALL OF US DUMBER.

This was a fabulous breakdown of current peer reviewed literature, and yet here we go with our closet climate science genius Trump Voter dumbasses making ALL of us dumber. Learn how to read you idiots.

Rebecca - the story does not change if you look at earlier years. Data for Puget Sound lowlands goes back to around 1895. The website to look at the data can be founded here; https://www.ncdc.noaa.gov/cag/time-series/us/45/3/tavg/12/12/1895-2017?base_prd=true&firstbaseyear=1901&lastbaseyear=2000

Thank you Cliff, for covering the beginning stages of runaway global warming. Your predictions seem on the safe side, which is understandable given the conservative nature of scientists. The positive feedback loops are hard to predict, but as they become the overriding factor in warming, we will begin to realize we underestimated their impact. Its amazing that our frozen tundra can keep all that gas underground. Once you take the amazingly complicated stability out our climate, things you never imagined will begin to happen. It's a big screen to watch and it will be a spectacular unfolding of events.

I agree with J, pure propaganda.Here in Eastern Washington we were once a dry bunchgrass desert. With Grand Coulee Dam and the Columbia Basin Irrigation Project we now have a breadbasket that feeds the World. We also have laws that require farmers to minimize dust in their farming operations by spraying water on access roads.

And the wildlife in Eastern Washington has flourished because of man's agricultural development of the Columbia Basin. We are now a major fly way of migratory waterfowl.

I'd be more worried about the BIG EARTHQUAKE that will eventually SHAKE Western Washington. Then your roadways will be inaccessible which will lead to chaos.

Given the lack of statistically significant warming trend in the Pacific Northwest, it would be interesting if at some point this blog could address glacial recession in the Cascades and what is driving that phenomenon. Unless there's either more heat or less precipitation, I don't understand why all the local glaciers are shrinking. What am I missing?

Michael Boyd - I've had the same question for a long time and wish Cliff would address it. Data I have looked at indicates that the earth's temperature has been in a range of +/- 1 deg. C since the last ice age. I don't quite recall how he stated it, but in Cliff's book he seems to imply that the glaciers that exist today are remnants of the last ice age and the mean temperature that the earth stabilized at is too high to sustain the glaciers. So they could be in a very term decline independent of recent climate change.

I'm a diversified subsistence farmer & trying to plan for crop infrastructure for winter growing plus next year. It sounds like this year so far might be a decent example of what to expect, i.e. long wet winters, mostly above freezing, a dank late start to spring, then flip a switch to long hot & dry summers. We're already using gravity drip watering systems as much as possible, but will add more rainwater catchment & possibly an in-ground pond for summer use. Tilling will need to be done in the fall before the ground is too saturated. Winter crops will need to wear layered outfits, just like Cascadian hikers. Wow.

For those of you saying this post is pure propaganda, please do something for all of us so that we can all attempt to feel slightly LESS DUMB just by reading your comment:

Lay it out for us. Explain how in THE HELL any scientist, Cliff Mass included, stands to benefit from sharing their research on climate warming? HOW THE HELL is this propaganda?? Do you really think these scientists are making millions of dollars? I heard one genius say, "Its that powerful green lobby that's profiting so much from global warming". Like seriously, powerful green lobby?? What in the hell is wrong with you people?

DRYSIDECOUG:

You don't see the profound lack of logic and evidence based thinking in your argument, do you? You do realize that you mentioned irrigation, right? Without that massive irrigation system in place, Eastern Wa. wouldn't grow a single apple. You represent our problem: Small-thinking uneducated STUPID people, who make America Dumber. You ONLY view the world from your own little biased microcosm, and you don't try to understand the larger world, nor do you care to.

What is the exact mechanism driving mountain glacier recession? If decreasing snowpack is not the culprit (yet), then the only other possible mechanism is increasing summer melt? From a mass balance perspective, it has to either be decreasing snow accumulation, or increased rate of melt.

Cliff: What data do you have on summer maximal temperatures? The graph that shows "number of days per year hotter than 90 degrees" would indicate that we have seen increasing numbers of super hot summer days. Could this alone be the culprit to glacier retreat?

I personally have documented profound changes in the terminus zones of the Coleman, Roosevelt, and Easton Glaciers on Mount Baker. Just since 2006 I've documented a 300 foot recession of Roosevelt glacier alone, as well as higher elevation glacial thinning. There are rock outcroppings visible now, that were under dozens of feet of glacier ice, as recently as 10 years ago!

Michael Boyd,Glacial recession? I suggest that you purchase and read this: https://www.amazon.com/Mount-Baker-Eruptions-Glaciations-Easterbrook/dp/0692620745The facts are somewhat more complicated than you might have thought.

Russell Cunningham, You wrote, "Glacier retreat, and glacier disappearance must be addressed..."

What do you suggest?

You also wrote, "Just since 2006 I've documented a 300 foot recession of Roosevelt glacier alone,..."You should read Easterbrook's book, which contains photographs showing the Roosevelt glacier above the two ledges that you must know about, taken in 1962. The Coleman Glacier terminus was farther downslope.In 1947, the terminus of Roosevelt Glacier was considerably upslope from where it is today, well above both ledges. I have photos taken in 2015 showing it at the upper ledge, but the book contains photos that demonstrate clearly how much the glacier has advanced and receded.

I don't have any quibble with the technical points made in this survey of Pacific NW climate scenario. Our proximity to the enormous cool reservoir of the NE Pacific Ocean gives us a buffer that most of the rest of the county does not enjoy.

But that does not imply that the Pacific Northwest will escape disastrous degradation from climate change. Granted, it will not be a direct effect, like Yuma AZ or Houston TX are likely to see. Rather, our disaster will be that the Pacific Northwest is part of extensive natural ecosystems and political orders that will be hammered elsewhere by climate change, and the hurt will spill over to us.

For example, suppose that the Pacific NW retains an equable climate, easy on the human metabolism, and kind to agriculture. But at the same time, huge populations across the "sunbelt" will be on the road again, as environmental refugees from a southern-tier climate shift that is not congenial for human metabolism. And the San Joaquin Valley's agriculture stands to be nuked by climate change. So, tens of millions of American citizens, and a vast agricultural deficit, will seek to relocate here.

And did I mention Mexico and Central America? Are those good people just going to stoically accept their fate as environmental victims and wither-in-place where they currently live? I don't think so. Rather, there will be a huge influx of environmental refugees diffusing northward.

So, bottom line, even as we continue OK in our climate in the coming century, the disaster unfolding for the South, the Southwest, southern California, Mexico, and Central America makes it likely that the Pacific NW will be a destination for tens of millions of environmental refugees, perhaps more. Such a number will swamp the region's ability to live sustainably, which we are already losing even at our "low" population.

There are no private reserves for the lucky few in a climate-warming future. Humans are incredibly plucky and determined to pursue their personal survival and family survival.

Celebration of our region's unique situation vis a vis global warming should not cause us to imagine that we will be left to live here undisturbed.

What about the contribution of the Pacific Decadal Oscillation (PDO)? We've been in the "warm" phase for almost 40 years now and one would think normal oscillation should soon lead us into a "cool" phase. How are the impacts of climate change in the decades ahead going to be influenced by this underlying natural variability? Do the models take this into account? Or how much might the warming change itself disrupt or override these cycles?

Cliff, Its good to see all this detail, but how meaningful is it really? You said that GCM's have little skill at predicting regional climate changes. They are not that great at predicting even global average temperatures. That's not surprising given the turbulent nature of the atmosphere and oceans and how complex the system is.

Seems to me we should prepare for climate change as we prepare for extreme weather events. Build robustness in infrastructure, stop subsidizing building at low elevations next to oceans and Puget Sound, etc. We should do those things anyway regardless of how serious climate change turns out to be.

I have not read that book, but I am aware of the documented glacier advances that occurred between approximately 1930 and 1980. The advances, however, were not very substantial. What's different about the recent recession of nearly every lower 48 Glacier since 1978 is the rate at which it is happening. In the 2014-15 summer alone, Cascade Glaciers lost as much as 5% of their total ice volume!

This is a great documented ongoing study:

http://www.nichols.edu/departments/Glacier/

As far as I know from the literature, and from talking with glaciologist colleagues, is that the only glaciers that experienced advance over the past 30 years have been the Emmons on the East side of Rainier, as well as Crater Glacier inside Mt. Saint Helens. The Emmons advanced during the 1990's because of a massive rockfall off of Little Tahoma Peak that blanketed the lower terminus zones in tens of feet of rock. This insulated the glacier for years, preventing melting. This advance however has since stopped, and the glacier is now rapidly receding and in a state of collapse at its lower elevations. The Crater Glacier is the fastest growing body of ice on the planet, but is a geologic anomaly, because it is so protected inside the crater, and is fed with tremendous avalanche accumulation.

In terms of overall Cascade Glacier volume being "much more extensive" later in the 20th century than in the beginning, this isn't entirely accurate. There was advance because of very mild cooling, but from what my research friends are telling me who work on this stuff, those advances have been far exceeded by the recent and rapid retreat that began in 1980.

Well.. CO2 has been proven to be a non free house warming gas. And the thing you shard is untrue. CO2 went from around 200 PPM to 420PPM in the last 100 years and the earth temperature trend has gone down rather then up over the last 5,000 years.

Bruce Kay,You're correct: we wouldn't want to pay attention to what two scientists with PhD's and experience in the field have to say about the subject, would we? Fortunately, Easterbrook's book contains many dated photographs and USGS contemporaneous maps to support his argument.

Don't you think that Pelto might be a little underweight in the CV department? In addition, since his research extends only to about 1980, isn't he likely to think that the trend since 1980 is a permanent trend, even if it almost certainly is not?

Given that it's difficult to attribute any single storm/drought to gw, is it not better to discuss instead in terms of how gw is increasing the probability of extreme weather?

"Global warming is contributing to an increased incidence of extreme weather because the environment in which all storms form has changed from human activities” -excerpt from "(Un)Natural Disasters: Communicating Linkages Between Extreme Events and Climate Change" this article can be found on the Global Meteorological Organization's website.

Thanks again, Cliff, for laying out the current science. I feel reassured by the fact that all sides feel a need to attack you. This just tells me that you are doing a great job of trying to find the truth while acknowledging just how hard that is. Ultimately, we are just human (really, just animals with oversized brains) and stuck in our own made up worlds. We think that we are smarter than we are and so we complain when scientists admit that we don't know for sure and damn when they get things wrong. Thank you for not succumbing to the urge to proclaim absolutes in this political climate and giving us information that can help us going forward.